[Determination of the activity of Willebrand's factor by laser analyzer of platelet aggregation]. / Opredelenie aktivnosti faktora Villebranda pri pomoshchi lazernogo analizatora agregatsii trombotsitov.

A modification of von Willebrand' factor/ristocetin cofactor activity test is proposed. Agglutination of formalin-treated platelets is monitored in the aggregation analyzer from changes in the light transmission in the specimen. The test is sensitive and reproducible. It is intended for clinical laboratories to be used in patients with hematological diseases and the endotheliopathy syndrome of different etiology.

[New methodical approach to the study of platelet aggregation in vitro]. / Novyi metodicheskii podkhod k issledovaniiu agregatsii trombotsitov in vitro.

A new approach to the investigation of the kinetics of platelet aggregation is described. The method is based on the analysis of light transmission fluctuations produced on the changes in the number of platelets in optical channel. The relative dispersion of the fluctuations of transmitted light intensity was used as a parameter to estimate the degree of platelet aggregation. Application of this method for the analysis of platelet aggregation permits to get new information about this process.

[Measurement of the concentration of free cytoplasmic calcium in the process of platelet aggregation using a fluorescent method]. / Izmerenie kontsentratsii svobodnogo tsitoplazmaticheskogo kal'tsiia v protsesse agregatsii trombotsitov fluorestsentnym metodom.

A multiwavelength method for measuring free cytosolic calcium concentration is proposed. It is based on the registration of the fluorescent spectrum of calcium--sensitive probe indo-1 and deconvolution of the spectrum into components corresponding to free and bound forms of the probe. Calcium concentration is calculated as a product of calcium-probe dissociation constant by calcium-bound to free form concentration ratio. The obtained values are independent of variations in light-scattering properties of the medium and total dye concentration in the optical channel. It is shown that during ADP-induced platelet aggregation calcium concentration rises without measurable delay after the addition of the inducer and significantly decreases by the time the aggregation begins.

[A new highly sensitive method of analysis of thrombocyte aggregation]. / Novyi vysokochuvstvite'lnyi metod analiza agregatsii trombotsitov.

The new method for studies of the platelet aggregation kinetics is based on the creation of a platelet stream through the optic canal and on an analysis of fluctuations in the intensity of the luminous flux that has passed through the sample. The relative dispersion of fluctuations in the intensity of the light passed through the sample is suggested as a parameter for the estimation of the platelet aggregation and for analysis of their aggregation kinetics. The method permits recording the platelet aggregation in citrate plasma, enriched for platelets, after exposure to the inductor in very low concentrations (0.05-0.15 microM ADP). Scanning electron microscopy has shown that aggregates are indeed formed in such cases, and they can be recorded from the increase of the relative dispersion in the fluctuations in the passed light intensity but cannot be recorded by Born's optic method.

[A decrease in the stimulated level of free intracellular calcium in thrombocytes during refractoriness]. / Snizhenie stimulirovannogo urovnia svobodnogo vnutrikletochnogo kal'tsiia v trombotsitakh pri refrakternosti.

The concentration of free intracellular calcium (Ca.f) was determined in ADP-stimulated platelets. Free calcium was measured by the multichannel method using fluorescent probe indo 1. In the presence of extracellular calcium, ADP induced a rapid reversible increase in Ca.f followed by reversible platelet aggregation. The second addition of ADP also induced increase in Ca.f and platelet aggregation, which were of lesser magnitude (platelet refractoriness). Without extracellular calcium, ADP also produced an increase in Ca.f. In this case the second addition of ADP also induced considerably less increase in Ca.f.

[Accumulation of acridine amino derivatives by electron-dense granules in thrombocytes]. / Akkumuliatsiia aminoproizvodnykh akridina élektronno-plotnymi granulami trombotsitov.

The uptake and release of dense bodies' content were studied using fluorescent amines. Real-time measurements of fluorescence spectra by a device developed on the basis of a multichannel optical analyzer and computer technique of spectrum deconvolution made it possible to investigate the kinetics of monoamine uptake and release in intact cells.

[Effect of alternating pressure on thrombin-stimulated thrombocytes]. / Vliianie peremennogo davleniia na trombin-stimulirovannye trombotsity.

The effect of alternating pressure on circulating platelet function was studied with particular reference to changes in platelet shape, aggregation and release reaction, MDA synthesis and intracellular calcium redistribution. Pressure effects were dependent on the magnitude of pressure impulses, platelet suspension storage time and the interval between the exposure to pressure and the challenge of platelets.

[Antiaggregating action on thrombocytes of a new anti-arrhythmia agent of the phenothiazine series--diethylamine ethmozine analog]. / Antiagregatsionnoe deistvie na trombotsity novogo antiaritmicheskogo preparata fenotiazinovogo riada--diétilaminovogo analoga étmozina.

A new antiarrhythmic drug of phenothiazine series diethylamine ethmozine analogue inhibited the rabbit's platelet aggregation induced by ADP, serotonin and thrombin. The degree of inhibition depended on the drug concentration and time of its incubation with platelets as well as on the inducer concentration. The transition from ADP-induced (5 microM) aggregation to reversible one was observed under the influence of relatively small doses of the drug. A gradual restoration of the platelet aggregating capacity occurred after washing platelets off the drug. The nonadditive character of the studied agent effects and that of theophylline on the platelets makes it possible to suppose that cAMP participates in the mechanism of the drug action on the platelets. The described antiaggregating effect of the drug on the platelets should be taken into account when it is used as an antiarrhythmic agent.

[Simultaneous recording of 4 thrombocyte functional parameters]. / Odnovremennaia registratisia 4 funktsional'nykh parametrov trombotsitov.

A method is offered for simultaneous measurement of four functional parameters of platelets: aggregation, cell shaped, adenine nucleotide release and redistribution of intracellular Ca2+. Variation in intracellular Ca2+ distribution in the course of processes induced by thrombin in platelets is described.

[Intracellular calcium redistribution in the thrombocytes during aggregation and release reaction]. / Issledovanie pereraspredeleniia vnutrikletochnogo kal'tsiia v trombotsitakh v protsesse agregatsii i reaktsii vysvobozhdeniia.

With the aid of an original installation there was simultaneously measured aggregation, reaction of release of adenine nucleotides, and redistribution of calcium (by fluorescence of calcium-sensitive probe of chlortetracyclin) in one sample of the suspension of washed platelets of rabbit. For the first time there was found an increase in the intensity of fluorescence in the presence of ADP-induced aggregation which continued long after the platelets desaggregation. The obtained results suggest that this increase indicating the redistribution of calcium ions in cells, is associated with the refractory state of the platelets.

[Action of KCN on intact and refractory thrombocytes]. / Deistvie KCN na intaktnye i refrakternye trombotsity

The effect of low KCN concentrations (5-10(4) M) on the ADP-induced aggregation of intact and refractory rabbit platelets was studied. KCN did not change the aggregation of the intact platelets, but stimulated that of the refractory platelets. The effect of the inhibitor stimulating the aggregation was not connected with the release of additional amounts of ADP. A different sensitivity of the aggregation capacity of the intact and refractory cells to the partial inhibition of metabolism was discussed in terms of the suggested earlier "calcium" model of autoregulation of platelet aggregation.

[The existence of a thrombocyte refractory state]. / K voprosu o sushchestvovanii refraktornogo sostoianiia trombotsitov

The degree of ADP-induced platelet aggregation was considerably decreased during incubation of platelet-rich plasma with ADP. The data obtained showed that neither inhibitory action of the excess of adenosine, nor ADP breakdown in the plasma could account for this phenomenon. The results seem to indicate the significance of refractory state of platelets for the regulation of their aggregability.

[ATP concentration in thrombocytes at different stages of ontogenesis]. / Soderzhanie ATF v trombotsitakh na otdel'nykh étapakh ontogeneza

Intraplatelet ATP levels were measured in rabbits of different ages by the firefly technique. Adult and 7-8 day rabbits platelets proved to contain 8.9 +/- 0.9 muM ATP/10(11) cells and 5.8 +/- 0.7 muM ATP/10(11) cells, respectively. The decreased ATP level in the 7-day rabbits' platelets was not related to the platelet isolation procedure.

[A comparative study of the functional characteristics of thrombocytes at different stages of individual development]. / Sravnitel'noe issledovanie funktsional'nykh osobennostei trombotsitov na otdel'nykh étapakh individual'nogo razvitiia

A comparative study of ADP-induced aggregation was made in adult rabbits' intact and refractory platelets and in 7-day rabbits' platelets in vitro. Platelets of the young animals resembled refractory those of adults. The effect of ADP on platelets in vivo did not depend on the age of animals. Changes in platelet population composition of adult and 7-day rabbits during standard isolation procedure were compared. The platelets in PRP of young rabbits were damaged to a greater extent than those of adult animals. It is suggested that the refractory state of young animal platelets in PRP as obtained with the standard technique, could be attributed to their decreased resistance against mechanical forces.